This type of displays using display devices emit, from their screens, not only visible rays that produce images, but also electromagnetic waves in a frequency band of megahertz to gigahertz (electromagnetic waves in this frequency band are hereinafter referred to simply as electromagnetic waves). In order to prevent electromagnetic interference (EMI) on electronic equipment that is caused by these electromagnetic waves, electromagnetic wave shielding materials having the function of bandpass filters, capable of transmitting visible rays but no electromagnetic waves, are mounted on the observer-side surfaces of the displays.
Of these electromagnetic wave shielding materials, a typical one comprises an electrical conductor layer of a metal such as copper or iron and a so-called electrical conductor mesh layer having a large number of visible-light-transmitting openings adjoining one another. In an electromagnetic wave shielding material of this type, a blackening layer, a film of a metallic oxide or the like, is usually formed on the observer-side external surface of the electrical conductor mesh layer, in order to prevent whitening of the displayed image and lowering of contrast that are caused by reflection of extraneous light from the metallic surface (see Patent Document 1).
Further, in order to obtain the electromagnetic wave shielding effect, it is necessary to ground the electromagnetic wave shielding material. For this purpose, a continuous electrical conductor layer having no openings is usually formed, as a frame portion, around the electrical conductor mesh layer (mesh portion) (see Patent Document 2). The frame portion passes no displayed image, so that it has no influence on display performance. To make the area of a screen as large as possible, the frame portion is made outside the screen in such a position that it cannot be seen from the outside when the screen is viewed.
Furthermore, in this type of a display having, on its front surface, an electromagnetic wave shielding material, the screen is trimmed with a black-colored light-shielding layer to make the display more attractive in design. In general, this black-colored light-shielding layer, a trim, is formed, by printing using black ink, on a predetermined outer edge portion of a glass plate to be laminated to and integrated into the electromagnetic wave shielding material (see Patent Document 3).
In addition, in the above displays, to indicate a manufacturer's designation, a product designation, or the like, the desired indication pattern is printed or embossed on a housing or frame by which the screen is surrounded because it is impossible to print or emboss the indication pattern on the screen surface. Further, in order for the indication pattern to glow when the power source is turned on, it is necessary to separately place a light source, such as a miniature electric bulb or an LED, on the rear of the indication pattern.
Patent Document 1: Japanese Laid-Open Patent Publication No. 134189/1986.
Patent Document 2: Japanese Laid-Open Patent Publication No. 233992/1999.
Patent Document 3: Japanese Laid-Open Patent Publication No. 9484/2002.
In the case where a display screen is, as mentioned above, trimmed with a black-colored light-shielding layer, a separate printing step is additionally needed for trimming, which leads to increase in the total number of steps and material cost. Further, to shield light emitted from around the screen, the black-colored light-shielding layer should have good light-shielding properties. In view of this requirement, the formation of the light-shielding layer by printing is disadvantageous because it is not easy to uniformly print the light-shielding layer with a large amount of high-pigment-content ink.
Furthermore, an attempt to indicate a manufacturer's designation, a product designation, or the like on the display inevitably leads to further increase in the total number of steps and material cost. Particularly, in order for the indication pattern to glow when the power source is turned on, an additional step and extra material cost are needed to separately place a light source, and, moreover, the light source consumes extra electric power.